Some Techniques for Manufacturing Fireworks (1) Dark Delay Compositions, (2) The Use of Metal Powders

Introduction: In recent years I have studied the oxidation and reduction taking place between various substances in a mixture. I reported on some of these studies in a paper titled “A Concept of Negative Explosives” presented in 1986 at the Eleventh International Pyrotechnics Seminar[1] in Vail, Colorado, USA. In the present paper, I will be presenting the follow-up work which I have performed under the above title.

The work was carried out using the oxygen value of the mixture to clarify the burning effects. The oxygen value denotes the excess (positive) or inadequate (negative) amount of oxygen generated in grams per 100 grams of mixture during the burn.

The term “dark delay composition” refers to a mixture which does not form a flame or spark that is visible from a distance. The effect can be used to prevent the formation of the trail from a flying firework. It is referred to for short in the following as “dark composition”.

When a metal is used as the component of a mixture, a special effect is generated. A report is given here on metal sparks, red lead explosive charges and water flares. The metals in question are magnesium, magnalium, aluminum, ferrotitanium and zirconium, whose effects are explained as a function of the properties of the metal, those of the oxygen carrier and the oxygen value of the mixture.

Ref: Selected Pyrotechnic Publication of Dr. Takeo Shimizu, Part 2,  pp 21-38

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